[Mesa-dev] [RFC] nir: add pass to lower atomic counters to SSBO
Rob Clark
robdclark at gmail.com
Thu Apr 13 15:23:32 UTC 2017
This is equivalent to what mesa/st does in glsl_to_tgsi. For most hw
there isn't a particularly good reason to treat these differently.
Signed-off-by: Rob Clark <robdclark at gmail.com>
---
This is part of a larger patchset I'm working on to add SSBO and compute
shader support in mesa/st glsl_to_nir path, and compute/SSBO support in
freedreno. Still working on a few things and some cleanup on the rest
of it, but I figured I should send this out to get some early comments.
src/compiler/Makefile.sources | 1 +
src/compiler/nir/nir.h | 1 +
src/compiler/nir/nir_lower_atomics_to_ssbo.c | 215 +++++++++++++++++++++++++++
3 files changed, 217 insertions(+)
create mode 100644 src/compiler/nir/nir_lower_atomics_to_ssbo.c
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 2455d4e..b2a3a42 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -208,6 +208,7 @@ NIR_FILES = \
nir/nir_lower_64bit_packing.c \
nir/nir_lower_alu_to_scalar.c \
nir/nir_lower_atomics.c \
+ nir/nir_lower_atomics_to_ssbo.c \
nir/nir_lower_bitmap.c \
nir/nir_lower_clamp_color_outputs.c \
nir/nir_lower_clip.c \
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index ce5b434..be35930 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2546,6 +2546,7 @@ void nir_lower_bitmap(nir_shader *shader, const nir_lower_bitmap_options *option
bool nir_lower_atomics(nir_shader *shader,
const struct gl_shader_program *shader_program);
+bool nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset);
bool nir_lower_to_source_mods(nir_shader *shader);
bool nir_lower_gs_intrinsics(nir_shader *shader);
diff --git a/src/compiler/nir/nir_lower_atomics_to_ssbo.c b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
new file mode 100644
index 0000000..f382e29
--- /dev/null
+++ b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright © 2017 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ * Rob Clark <robclark at freedesktop.org>
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+
+/*
+ * Remap atomic counters to SSBOs. Atomic counters get remapped to
+ * SSBO binding points [0..ssbo_offset) and the original SSBOs are
+ * remapped to [ssbo_offset..n) (mostly to align with what mesa/st
+ * does.
+ */
+
+static bool
+lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
+{
+ nir_intrinsic_op op;
+ switch (instr->intrinsic) {
+ case nir_intrinsic_ssbo_atomic_add:
+ case nir_intrinsic_ssbo_atomic_imin:
+ case nir_intrinsic_ssbo_atomic_umin:
+ case nir_intrinsic_ssbo_atomic_imax:
+ case nir_intrinsic_ssbo_atomic_umax:
+ case nir_intrinsic_ssbo_atomic_and:
+ case nir_intrinsic_ssbo_atomic_or:
+ case nir_intrinsic_ssbo_atomic_xor:
+ case nir_intrinsic_ssbo_atomic_exchange:
+ case nir_intrinsic_ssbo_atomic_comp_swap:
+ case nir_intrinsic_store_ssbo:
+ case nir_intrinsic_load_ssbo:
+ /* keep same opcode, remap buffer_index */
+ op = instr->intrinsic;
+ break;
+ case nir_intrinsic_atomic_counter_inc:
+ case nir_intrinsic_atomic_counter_add:
+ case nir_intrinsic_atomic_counter_dec:
+ /* inc and dec get remapped to add: */
+ op = nir_intrinsic_ssbo_atomic_add;
+ break;
+ case nir_intrinsic_atomic_counter_read:
+ op = nir_intrinsic_load_ssbo;
+ break;
+ case nir_intrinsic_atomic_counter_min:
+ op = nir_intrinsic_ssbo_atomic_umin;
+ break;
+ case nir_intrinsic_atomic_counter_max:
+ op = nir_intrinsic_ssbo_atomic_umax;
+ break;
+ case nir_intrinsic_atomic_counter_and:
+ op = nir_intrinsic_ssbo_atomic_and;
+ break;
+ case nir_intrinsic_atomic_counter_or:
+ op = nir_intrinsic_ssbo_atomic_or;
+ break;
+ case nir_intrinsic_atomic_counter_xor:
+ op = nir_intrinsic_ssbo_atomic_xor;
+ break;
+ case nir_intrinsic_atomic_counter_exchange:
+ op = nir_intrinsic_ssbo_atomic_exchange;
+ break;
+ case nir_intrinsic_atomic_counter_comp_swap:
+ op = nir_intrinsic_ssbo_atomic_comp_swap;
+ break;
+ default:
+ return false;
+ }
+
+ b->cursor = nir_before_instr(&instr->instr);
+
+ /* easy case, just remap SSBO buffer index: */
+ if (op == instr->intrinsic) {
+ unsigned srcn = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
+ nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[srcn], 1);
+ nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b, ssbo_offset));
+ nir_instr_rewrite_src(&instr->instr,
+ &instr->src[srcn],
+ nir_src_for_ssa(new_idx));
+
+ return true;
+ }
+
+ nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
+ nir_ssa_def *temp = NULL;
+ nir_intrinsic_instr *new_instr =
+ nir_intrinsic_instr_create(ralloc_parent(instr), op);
+
+ /* a couple instructions need special handling since they don't map
+ * 1:1 with ssbo atomics
+ */
+ switch (instr->intrinsic) {
+ case nir_intrinsic_atomic_counter_inc:
+ /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
+ temp = nir_imm_int(b, +1);
+ new_instr->src[0] = nir_src_for_ssa(buffer);
+ new_instr->src[1] = instr->src[0];
+ new_instr->src[2] = nir_src_for_ssa(temp);
+ break;
+ case nir_intrinsic_atomic_counter_dec:
+ /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
+ /* NOTE semantic difference so we adjust the return value below */
+ temp = nir_imm_int(b, -1);
+ new_instr->src[0] = nir_src_for_ssa(buffer);
+ new_instr->src[1] = instr->src[0];
+ new_instr->src[2] = nir_src_for_ssa(temp);
+ break;
+ case nir_intrinsic_atomic_counter_read:
+ /* remapped to load_ssbo: { buffer_idx, offset } */
+ new_instr->src[0] = nir_src_for_ssa(buffer);
+ new_instr->src[1] = instr->src[0];
+ break;
+ default:
+ /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
+ new_instr->src[0] = nir_src_for_ssa(buffer);
+ new_instr->src[1] = instr->src[0];
+ new_instr->src[2] = instr->src[1];
+ if (op == nir_intrinsic_ssbo_atomic_comp_swap)
+ new_instr->src[3] = instr->src[2];
+ break;
+ }
+
+ nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
+ instr->dest.ssa.num_components,
+ instr->dest.ssa.bit_size, NULL);
+ nir_instr_insert_before(&instr->instr, &new_instr->instr);
+ nir_instr_remove(&instr->instr);
+
+ if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
+ b->cursor = nir_after_instr(&new_instr->instr);
+ nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
+ nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
+ } else {
+ nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
+ }
+
+ return true;
+}
+
+bool
+nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
+{
+ bool progress = false;
+
+ nir_foreach_function(function, shader) {
+ if (function->impl) {
+ nir_builder builder;
+ nir_builder_init(&builder, function->impl);
+ nir_foreach_block(block, function->impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type == nir_instr_type_intrinsic)
+ progress |= lower_instr(nir_instr_as_intrinsic(instr),
+ ssbo_offset, &builder);
+ }
+ }
+
+ nir_metadata_preserve(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ }
+ }
+
+ if (progress) {
+ /* replace atomic_uint uniforms with ssbo's: */
+ unsigned replaced = 0;
+ nir_foreach_variable_safe(var, &shader->uniforms) {
+ if (glsl_get_base_type(var->type) == GLSL_TYPE_ATOMIC_UINT) {
+ exec_node_remove(&var->node);
+
+ if (replaced & (1 << var->data.binding))
+ continue;
+
+ nir_variable *ssbo;
+ char name[16];
+
+ // TODO can we declare an array without size? Or do we have
+ // to find all the atomic_uint's in one pass and figure out
+ // max offset??
+ const struct glsl_type *type =
+ glsl_array_type(glsl_uint_type(), 256);
+
+ snprintf(name, sizeof(name), "counter%d", var->data.binding);
+
+ ssbo = nir_variable_create(shader, nir_var_shader_storage,
+ type, name);
+ ssbo->data.binding = var->data.binding;
+
+ replaced |= (1 << var->data.binding);
+ }
+ }
+ }
+
+ return progress;
+}
+
--
2.9.3
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